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914World.com _ 914World Garage _ Longevity/reliability of a "sleeved" helicoil timesert spark plug hole

Posted by: nditiz1 Jan 21 2025, 06:08 PM

I recently acquired a 912e aka 2.0 Ljet. I was told it was running up until the point the 912e was disassembled. I find it very hard to believe when spark plug #4 hole does not thread a m14 spark plug. I will check an m16 bolt tomorrow when the hardware store opens as that is close to what I get with a micrometer. Now the hole is threaded. If I can get a m16 -> m14 reducer how well will it hold up? Should I only use a helicoil or even a timesert? OR if it does accept m16, get a studebaker m16 spark plug and gap accordingly?
Thanks all!

Posted by: technicalninja Jan 21 2025, 06:17 PM

Sorry, I think you're TOAST!

Looks like a time-sert came out!

I'd take that apart, check for other damage/cracks and have a machine shop weld that back up if the casting is good otherwise.

You're almost there anyways...

Strange to see intake bolted on with no tins.

Do 912 tins fit OVER the intakes?

I didn't think they did.

Posted by: Montreal914 Jan 21 2025, 07:56 PM

Knowing how the stock 2liter heads all crack here (picture) I would highly doubt with the reduced wall created by that insert your head wouldn't be cracked...

If once removed the heads are worthy of rebuild, I would seriously consider having them welded and drilled for 12mm plugs in hopes of avoiding future cracks.

Attached Image

Posted by: Chad911sc Jan 28 2025, 04:14 PM

When I presently pulled my 2.0 apart, all 4 spark plug holes were cracked on both sides. They were also cracked where the cylinders meet the head….straight to the trash.
Remember these are 50 years old now.

Posted by: technicalninja Jan 28 2025, 04:32 PM

I recycle anything aluminum...

Now, when I go, I'm pulling a trailer loaded to the top with AC condensers/radiators/compressor cores.

Usually worth $300-400 in "rat hole" money!

Posted by: Artfrombama Jan 28 2025, 08:04 PM

FWIW;
I was told many years ago by an old VW mechanic to NEVER put a Champion spark plug in a VW, the plating will cause them to seize in the head.